A touch screen device means an input unit for performing the whole control of an electronic device; comprising controlling a display screen by sensing a touch point of user on the display screen and then using the information about the sensible touch point as input information.
The touch screen device uses a touch screen, such as a resistive touch screen, a capacitive touch screen, an ultrasonic touch screen, an optical (infrared) sensor touch screen, an electron inducing touch screen, and the like. They have different characteristics, such as signal amplification, a resolution, the level of difficulty of plan and process technology, and the like, according to each way. Therefore, the touch screen device has to reflect and select enough to be able to emphasize each way's advantage.
For specifically selecting a way, durability, an economic feasibility, and the like should be considered in addition to an optical property, a technical property, and an input property. Two representative ways from among these are the resistive way and the capacitive way. From among these, the capacitive touch screen that is applied to Mobile, MP2 device, Note Book, and the like, generally uses ITO (Indume Tin Oxide) transparency electrode.
FIG. 1a is a cross-sectional view of a touch panel including ITO material according to the prior art; FIG. 1b and FIG. 1c are processes for manufacturing a touch panel including ITO material according to the prior art, which are flow charts of a photo etching process and a screen printing process, respectively.
Referring to FIG. 1a, the touch screen using the capacitive way according to the prior art has poor touch sensitivity because sensing and motion sensors are formed by patterning ITO transparency electrode, so that it is not suitable for making a large area. In addition, an optical transmittance is not good and also visibility is bad due to the pattern of sensor electrode.
Referring to FIGS. 1b and 1c, the touch panel according to the prior art is manufactured by the photo etching process for forming a wiring and a pattern of ITO transparency electrode or a screen-printing process for forming a pattern of silver electrode.
In the case of the photo etching process, the process is complex and the cost of manufacturing is high due to a photolithography process. In the case of the screen-printing process, the process is difficult to accurately control so that it is difficult to maintain an accurate align tolerance between ITO and outer electrode part; a line width is difficult to finely implement so that there are many dead spaces; a crack may be generated on the ITO micro line width part due to the high-temperature drying; and the cost of ITO material is high so that the cost for manufacturing the touch screen and touch pad including ITO material is high.